Trajectory of muscle strength and functional performance after ACLR

Michael Girdwood

Hi! 👋

My name is Mick.

  • I am a physiotherapist, researcher and PhD Student at La Trobe University.
  • I’ve worked across a variety of projects in musculoskeletal health, focusing at the moment on knee and hip injuries
  • m.girdwood@latrobe.edu.au

Hi! 👋

My name is Mick.

  • Born in Budapest 🇭🇺 , raised in Melbourne 🇦🇺
  • Practiced physio in Melbourne and Tokyo
  • Sports experience:
    • Australian rules football
    • Football (soccer)
    • Tennis (ITF tour)
    • Waterpolo

Hi! 👋

My name is Mick.

  • Worked at La Trobe University since 2016
  • Tendons -> Hips -> Knees
  • Commenced PhD in late 2020
    • nearly finished!

Kambhampati & Vaishya, 2019

Aims

How does muscle strength and funcional performance change over time after ACLR

  1. compared within-person (i.e. to the uninjured contralateral limb)
  2. compared between-person (i.e. to uninjured healthy populations)

Methods

A group of systematic Reviews with meta analysis

  1. Quadriceps and hamstring strength
  2. Hop performance
  3. Hip and lower leg strength

Databases: MEDLINE, EMBASE, CINAHL, Scopus, Cochrane CENTRAL, SPORTDiscus

Inclusion criteria: primary ACL injury, aged 18-40 years, with a quantitative measure of muscle strength or hop performance

Methodological Quality Assessed on domains outlined by Cochrane Collaboration

Comparison:

  • to the contralateral leg
  • to an uninjured control group

Methods

A group of systematic Reviews with meta analysis

  1. Quadriceps and hamstring strength
  2. Hop performance
  3. Hip and lower leg strength

Additional Criteria:

  • Published from 2010 onwards
  • Minimum sample size of n=50

Effects - Ratio of Means

Effects - Ratio of Means

\[\begin{equation} RoM = \frac{90Nm}{100Nm} \end{equation}\]



Example: ACL Side compared to the contralateral side

ROM = 0.9 95%CI[0.85-0.95]

= ACL side is 0.9x weaker than the contralateral side

= 10% deficit in ACL side strength

Longitudinal/multivariate meta-analysis

Allow multiple (correlated) pieces of information from the same study to be included in a meta-analysis

flowchart TD
  A{Crossley et al} --> B(3 months)
  A--> C(6 months)
  A--> D(12 months)
  • timepoints
    • same people measured over time
  • outcomes
    • same people measured for linked or correlated outcomes (e.g. separate measure for anxiety and depression)
  • comparisons
    • same control groups for different comparators

Data Analysis

  • Mixed-effects meta-analysis with a REML estimator using metafor package.
  • Quadriceps and hamstring, separated by contraction type:
    • Slow concentric ≤120°/s
    • Fast concentric >120°/s
    • Isometric


Random effects:

(timepoint | cohort)

  • timepoints, nested within cohorts

Fixed effect: timepoint

  • linear, log linear, polynomial, 3-knot spline and 4-knot spline

Robust variance estimation methods using clubSandwich package 🥪

Results

  • 233 studies 🥵
  • 🇦🇺 🇬🇧 🇺🇸 🇮🇷 🇯🇵 🇹🇷 🇧🇷 🇳🇴 🇰🇷 🇸🇪 🇨🇭 🇸🇮 🇳🇱 🇬🇷 🇵🇱 🇦🇹 🇮🇹 🇩🇪 🇹🇼 🇳🇴 🇸🇬 🇶🇦 🇨🇳 🇪🇸 🇨🇦 🇩🇰 🇧🇦 🇹🇭
  • 31,234 ACLR participants; 3049 controls; (40% women)
  • Mean age: 18-38 years, median 25
  • Mean BMI: 21.3 to 28.4 kg/m2; median 24.2
  • Most common timepoints:
    • 3 months (k=35)
    • 6 months (k=88)
    • 12 months (k=59)

Knee extensors (quadriceps)

Slow concentric knee extensor

Fast concentric knee extensor

Isometric knee extensor

Knee flexors (hamstrings)

Slow concentric knee flexor

Fast Concentric knee flexor

Isometric knee flexor

Graft Type

Extensor grafts ~ Quads Strength

  • Extensor graft - PT, BPTB
  • Other graft - HS, Achilles, Allograft
  • Extensor graft ≈ 0.9 fold lower extensor strength

Flexor grafts ~ Hamstring Strength

  • Flexor graft - HS (any type)
  • Other graft - PT, BPTB
  • Flexor graft ≈ 0.84 to 0.91 fold lower flexor strength

Which leg to compare to?

Exploratory Analysis

What to compare test outcome to?

  • contralateral limb (e.g. LSI)
  • uninjured control limb (e.g. case control studies)



  • Several studies report both comparisons on the same patients

Is comparing to the contralateral limb equivalent to comparing
to uninjured controls

Bivariate Analysis

Between-person deficits were 1.53x greater than within person (95%CI 1.15 to 2.19)

Muscle Strength Summary


Take aways

  • Potentially significant deficits at 1 year post-ACLR persist beyond 5 years+
  • Deficits span different contraction types
  • Graft morbidity might contribute 10-15% increased deficits
  • Comparing within-person probably underestimates the amount of strength deficit


Limitations

  • Impact of rehabilitation is unclear
  • Major variability in strength seen - wide range of possible scenarios post injury
  • Much less data comparing between people (i.e. controls)
  • Lack of data for eccentric contractions

Hop Performance

Background

  • The last review of functional performance measures was published 10 years ago (Abrams et al 2014, AJSM)
  • Only data on the first 2 years post surgery included

Background

  • The last review of functional performance measures was published 10 years ago (Abrams et al 2014, AJSM)
  • Only data on the first 2 years post surgery included


Hop tests are widely used by clinicians after ACLR (>90%)

  • What are the long term changes in hop performance?
  • What to expect for our patients?

Results

  • 136 studies
  • 🇦🇺 🇬🇧 🇺🇸 🇮🇷 🇯🇵 🇹🇷 🇧🇷 🇳🇴 🇰🇷 🇸🇪 🇨🇭 🇸🇮 🇳🇱 🇬🇷 🇵🇱 🇦🇹 🇮🇹 🇩🇪 🇹🇼 🇳🇴 🇸🇬 🇶🇦 🇨🇳 🇪🇸 🇨🇦 🇩🇰 🇧🇦 🇹🇭
  • 21,876 ACLR participants; 1484 controls; (36% women)
  • Mean age: 18-38 years, median 27
  • Mean BMI: 21.9 to 28.0 kg/m2; median 24.3
  • Most common timepoints:
    • 6 months (k=36)
    • 1 year (k=31)
    • 2 years (k=15)

Results

  • 6 most commonly reported hop tests:
    • single forward
    • triple forward
    • triple crossover
    • 6m timed
    • side hop
    • vertical hop

Hop Performance

Relationship between different hops

Hop Performance Summary


Take aways

  • Evaluating only forward hop tests might underestimate deficits
  • Mean hop performance may be similar between limbs when measured 2-3 years post-ACLR
    • ? mechanism
  • Performance on forward hop tests are highly correlated, choose one?


Limitations

A similar story to the muscle strength data:

  • Impact of rehabilitation is unclear
  • Major variability in hop performance seen - wide range of possible scenarios post injury
  • Very limited between-person comparisons

Beyond the thigh muscles: Hip and lower leg muscle strength after ACLR

Why might the hip and calf muscles be important?

  • important contributions to frontal plane knee stablity Maniar, 2022
  • potential link between impaired hip strength and worse knee OA outcomes Hall, 2017
  • gastrocnemius also contributes to knee stability and compression forces Mokhtarzadeh, 2013
  • hip and calf muscle strengthening included in rehabilitation trials Culvenor 2023; Beard 1998; Hohman 2011
  • hip muscle weakness seen in many other knee conditions (e.g. PFJ pain, PT, non-traumatic OA)

Overview

  • 28 studies 🇦🇺 🇬🇧 🇺🇸 🇮🇷 🇯🇵 🇩🇪 🇹🇷 🇧🇷 🇳🇴 🇰🇷

  • 1103 ACL injured (all except 12 reconstructed) + 1145 controls

  • Mean age ranging from 19 to 38 years

  • Most timepoints between 7-12 months post ACL surgery

  • Limited information on activity levels

    • n=5 athletes
    • n=4 ‘recreationally active’
    • n=6 with Tegner scores (range 5-7)

Comparison within person

Comparison with uninjured controls

Discussion



No consistent or widespread weakness of the hip or calf muscles after ACL injury

Despite all studies included showing significant quadriceps and hamstring weakness when measured


Limitations

  • Low sample size especially for hip IR, flexion, soleus and dorsiflexors

  • Variability and heterogeneity

  • Very low certainty evidence

What is the significance of physical capacity changes after ACL injury?

What is the significance of physical capacity changes after ACL injury?

Do changes in strength and function matter?

What we know

  • Hop testing and muscle strength tests are key elements of RTS testing
  • Passing thresholds on a battery of tests probably reduces reinjury risk

What we know

  • Strong relationships between functional test performance and knee related outcomes in the first 6-12 months post injury
  • Is this cause and effect, or two metrics improving simultaneously?

Can we use hop performance to guide expectations and prognosis of patients?

  • Evidence from 2 recent SRs is shaky

  • Losciale 2020
    • no or fair correlation between hop testing and self-reported outcomes >2 years
  • West 2023 SR
    • Using a cut-off of 90% LSI: 2.5x odds of better symptoms
    • ? Driven by studies in 1st 2 years post injury?

KOALA Prospective Cohort


  • 123 men and women

  • Aged 18-50 years

  • Recruited at 1 year post-ACLR

  • ACLR with hamstring graft from 2 Melbourne surgeons

  • No structured rehabilitation

  • Measured at 1, 3, 5 and 11 years (Culvenor, 2016, 2017; Patterson 2018, 2019, 2020)

Outcomes



PROMS

  • Knee related: KOOS, IKDC
  • Quality of life: ACL QOL, EQ5D
  • Activity levels / return to sport status
  • New injuries

Physical Tests

  • hop tests: single forward, triple crossover, side
  • one-leg rise test
  • clinical, laxity, crepitus etc

Imaging

  • MRI at 1 and 5 years
  • Xray at 1, 5 and 11 years

`

The Population


n = 123
Women (%) 43 (35%)
Age (years) 29.9 (8.8)
BMI (kg/m2) 26.1 (3.9)
1 year KOOS4 81.1 (11.5)

Mean (SD) unless specified

The Population


n = 123
Women (%) 43 (35%)
Age (years) 29.9 (8.8)
BMI (kg/m2) 26.1 (3.9)
1 year KOOS4 81.1 (11.5)

Mean (SD) unless specified

The Population


n = 123
Women (%) 43 (35%)
Age (years) 29.9 (8.8)
BMI (kg/m2) 26.1 (3.9)
1 year KOOS4 81.1 (11.5)

Mean (SD) unless specified

Quality of Life

Pain

Sport

Subsequent Knee Events

Total n = 117 Index
knee		 Contra
knee
ACL rupture 6 5
Arthroscopy 7 2
Meniscal surgery 3 1
Meniscal injury 2 0
Collateral ligament 2 2
Cartilage injury 1 0
Knee effusion 0 2
Total 21 12

- Generalised linear mixed models with an ordered-beta distribution - Random effects for participants

Pain

  • A modest relationship between better 1 year hop performance and better future knee outcomes.
  • Unlikely to be clinically meaningful +10cm increase = 0.6% better KOOS-Pain
  • Individual variability > hop performance

Quality of Life

  • Non-linear relationship: single-leg hop >108cm = no relationship
  • ?clinically meaningful

Summary

  • Hop performance at 1 year post-ACLR has a modest relationship to future self-reported knee outcomes
  • Very poor hop performance might indicate groups at risk of poor prognosis
  • Not clinically useful at an individual level

  • Fits in with the previous systematic reviews

    • Modest relationships in some contexts

  • Still unclear whether prognosis can be modified by intervening on functional performance and muscle strength in the medium-term post-ACLR

  • Watch this space!

Potential clinical implications

  • Knee health status was largely stable over a 10 year period
  • Having a better hop performance does not guarantee good future knee-related quality of life
    • having very poor performance might be the only useful information?
  • By 10 years, 1 in 4 may have had a subsequent knee injury/event

Is hip rotation strength implicated in symptomatic and structural osteoarthritis outcomes after anterior cruciate ligament injury?

Michael Girdwood, Adam Culvenor, Brooke Patterson, Ali Guermazi, Tim Whitehead, Hayden Morris, Ebonie Rio, Kay Crossley

Physical Therapy in Sport, 2023

Research Question:

  • How does hip strength differ between the injured and non-injured side in people 1-year after ACLR?
  • Is hip strength associated with functional, symptomatic and structural outcomes?

Participants





Methods

Hip External Rotation & Internal Rotation with HHD

Measured only at 1 year with hand held dynamometer according to Kemp et al 2013, JSAMS protocol

Methods: Outcomes and Analysis

Association to Symptoms

  • Greater hip ER & IR strength was associated with superior AKPS at 1 and 5 years.

Assocation to Structure (Imaging)

  • Lower hip ER strength was associated with worsening tibio-femoral cartilage lesion score at 5 years


🔻0.1Nm Strength = Odds Ratio: 1.64 (95%CI 1.09 to 2.50)


  • No other significant relationships identified (patellofemoral cartilage worsening or osteoarthritis)

Discussion

  • Hip ER may influence symptomatic and structural outcomes as it is critical to single leg functional tasks.

  • Relationships are modest, and likely multi-factorial - need further confirmation

  • ER specific weakness could result from:

    • lack of training/rehab

    • weakness broadly of the entire lower limb (not specific to the hip).

Key Summary

  • Hip ER strength was impaired on the injured side at 1 year post ACLR

  • This may contribute to symptomatic, and structural outcomes up to 5 years post-operatively.

  • Contrary to initial hypothesis, hip rotation strength was not associated with PFJ structure

Thank you ++

Questions?

m.girdwood@latrobe.edu.au

Research Question:

  • What is the relationship between thigh muscle strength and self-reported function at more than 2 years post ACLR?
  • Is this relationship different in a cohort who run regularly compared to those with ongoing symptoms

Methods - Participants

n = 120
Men and women post-ACLR
Aged 18-50 & >2 years post surgery

Runners

  • n = 33
  • running ≥3x / week
  • ≥10km / week

Symptomatic Cohort

  • n = 87
  • 24-36 months post ACLR
  • KOOS4 <80/100

Methods - Strength Assessment







Peak isometric
quadriceps (knee extension) and hamstring (knee flexion) torque

Methods - Self-reported outcomes


Knee Osteoarthritis Outcome Score - KOOS

  • Pain
  • Symptoms
  • Daily Living
  • Sport & Recreation
  • Quality of Life
  • Patellofemoral
  • KOOS4 - Average of Pain, Symptoms, Sport & Recreation, Quality of Life subcales


Data-analysis

Beta-regression models modelled the relationship between muscle strength and self-reported function (KOOS subscales).

Results - The Population

Measure Runners (n = 33) Symptomatic (n = 87)
Age (years) 32 (7) 31 (6)
% Female 36% 36%
BMI (kg/m2) 23.8 (2.8) 27.9 (5.7)
Time since surgery (yrs) 9.2 (7.4) 2.7 (0.3)
KOOS4 83.0 (15.9) 65.6 (12.8)
Quadriceps Strength (Nm) 207.5 (54.8) 184.2 (59.7)
Hamstring Strength (Nm) 97.4 (26.3) 83.1 (29.0)


  • The runners had stronger quadriceps and hamstrings, and reported less symptoms.

  • Time since surgery was not related to muscle strength.

No meaningful relationships between thigh muscle strength and self-reported function

Findings were consistent for both runners and symptomatic cohorts (no interaction effect).

Results

  • Example: KOOS4 Subscale
    • 10 Nm greater strength = 0.3% higher KOOS4 .font90[(95%CI -0.3 to 0.9%)]

Discussion

  • Our findings consistent with most existing literature >2 years post ACLR (Ericsson 2013; Flosadottir, 2016; Norte, 2018; Moller 2009).


  • Psychological factors could contribute more to longer-term symptomatic outcomes (Filbay, 2021)


Key Summary

  • Thigh muscle strength was not associated with self-reported function in people >2 years post-surgery

  • Findings were consistent in a group of runners and a lower functioning symptomatic cohort.

  • Other non-physical factors may be more important to longer term knee health